I had a go on a gas-powered one in the summer and was shooting straight through empty beer cans on a fence without knocking them off from 50 yard about.
Cost about £600 I think. But yeah I've got like 10 airguns knocking about the place, it'd be a pisstake to have to have a licence for them. The same argument can apply to cars as well, its a case of the individual's negligence that needs to be addressed more than anything.
Mind you I do know of someone who accidentally shot his postlady in the head with an air rifle and ended up with armed police outside his house.
He actually said "I've shot the postlady!!!" on his 999 call.

just cause they're a really crap type of gun doesn't make them totally harmless. off the top of my head I can remember about 8 times I've heard aboutt deaths from air rifles on the news, in my wee short life. A lot of them are accidental but there have been lots of 'cross-fire' incidents in which young children get hit.